The Internet and the proliferation of many forms of customer premises equipment have prompted increasing demand for subscriber connections to the telecommunications network. Existing copper cabling carrying a single voice or data channel have traditionally been used to connect subscribers to the central office. Because the expense associated with placing additional copper cabling from the central office to the subscribers is prohibitive, a solution to provide additional subscriber connections with existing copper cabling is the pair gain equipment. The pair gain equipment enables the same copper cabling or twisted pair to carry multiple channels of telecommunications traffic signals to multiple subscriber lines from the central office.
Related technical references includes Bellcore GR-303-CORE, Generic Requirements for Integrated Digital Loop Carrier System, Issue Sep. 1, 1995; TR-NWT-000057, Functional Criteria for Digital Loop Carrier Systems, Issue Jan. 2, 1993; TR-TSY-000008, Digital Interface Between SLC 96 Digital Loop Carrier and a Local Digital Switch, Issue Aug. 2, 1987, Revision Sep. 1, 1993; and ANSI T1.401, Interface Between Carriers and Customer Installations Analog Voicegrade Switched Access Lines Using Loop-Start and Ground-Start Signalling, 1988. These references are incorporated herein by reference.